public class code5 {
    public int maxProfit(int k, int[] prices) {
        int INF = 0x3f3f3f3f;
        int n = prices.length;
        //细节优化
        k = Math.min(k,n/2);

        int[][] f = new int[n][k+1];
        int[][] g = new int[n][k+1];

        for(int i=1;i<k+1;i++) f[0][i] = g[0][i] = -INF;
        f[0][0] = -prices[0];

        for(int i=1;i<n;i++) {
            for(int j=0;j<k+1;j++) {
                f[i][j] = Math.max(f[i-1][j],g[i-1][j]-prices[i]);
                g[i][j] = g[i-1][j];
                if(j-1>=0) g[i][j]=Math.max(g[i][j],f[i-1][j-1]+prices[i]);
            }
        }

        int ret = g[n-1][0];
        for(int i=1;i<k+1;i++) ret = Math.max(ret,g[n-1][i]);
        return ret;
    }
}
